1. Field of the Invention
This invention pertains generally to wall panels, and more particularly to an acoustical wall panel which possesses a high noise reduction coefficient and a high sound transmission coefficient while additionally possessing sufficient strength to permit fixtures and accessories to be hung thereon.
2. Description of the Background Art
Wall structures formed from a plurality of interconnected, prefabricated and portable panels are used extensively in commercial and industrial buildings for dividing interior regions into smaller work regions. Such structures have proven particularly effective in providing greater privacy within the building, and at the same time improving the interior appearance. For this purpose, the panels are provided with many different exterior finishes, such as colored plastics, carpets and fabrics. Some of these panels also tend to minimize noise, particularly when they are provided with soft exterior finishes, such as by being covered with carpeting or fabric. Many panels of this type are also provided with slotted rails extending vertically along the edges thereof, whereupon fixtures such as work surface tops, shelves, filing cabinets and the like can be mounted on the panels. Due to the desire to mount these fixtures on the panels, the panels thus must be provided with substantial strength and, accordingly, current panels are normally provided with a relatively strong and rigid core so as to provide the necessary strength.
While panels of the above type do tend to minimize noise, nevertheless any noise absorption capability of the panel is normally provided solely by the outer coverings. Further, since these panels are normally of a height, substantially less than the floor-to-ceiling height, this also permits the transmission of substantial noise over the panel which, when coupled with the inability of these panels to absorb a high percentage of sound at various frequencies, thus results in poor sound reduction. Because of this inability to absorb a high percentage of the sound in the environment, these known panels have conventionally been referred to as non-acoustical-type panels.
In an attempt to provide a panel capable of absorbing a high percentage of directed sound at various frequencies, there are known several so-called "acoustical-type" panels which are more effective in absorbing the environmental noises surrounding the panels. However, to achieve this noise absorption capability, these panels normally comprise a fiberglass core with fabric coverings, the core being surrounded by a rectangular frame which constitutes the sole structure for providing the panel with structural strength. These panels, due to the lack of a significant structural design within the core, do not possess the strength and rigidity necessary to permit fixtures such as shelves and the like to be hung thereon. Further, these known acoustical panels possess limited durability and are easily damaged due to the softness and lack of strength possessed by the core of the panel.
In recognition of the need for an acoustical panel, the American Society of Testing Materials (ASTM) has defined industry standards for testing the sound absorption quality of movable partitions. These standards require that a panel be tested at sound wave frequencies of 250, 500, 1000 and 2000 cycles per second. The panel is rated on a scale of from 0 to 1.0, and the greater the sound absorption capability of the panel, the higher the numerical rating. This numerical rating, which is normally referred to as the Noise Reduction Coefficient (NRC), is averaged over the four test frequencies set forth above. Furthermore, a Sound Transmission Coefficient (STC) is used as an indicator of the amount of sound transmitted through the panel, on a scale of from 0 to 100, wherein higher numerical ratings denote less sound transmission. At the present time, the known acoustical panels which are capable of having fixtures hung thereon do not have satisfactorily high NRC's and STC's, whereas the known acoustical panels which utilize a core constructed totally of fiberglass are relatively weak and unstable, and often do not permit fixtures and the like to be hung thereon. As can be seen, therefore, in order to achieve stability, noise reduction is sacrificed.
Therefore, there is a need for an acoustical type panel having a high noise reduction coefficient and a high sound transmission coefficient which provides sufficient structural integrity to support fixtures such as shelves, cabinets and the like. The present invention satisfies that need, as well as others, and overcomes the deficiencies found in prior panels.